Backflow Testing in Ontario, CA

Does my Ontario property need a backflow assembly?

That call belongs to the Water Quality Programs Division of the Ontario Municipal Utilities Company, the city-owned utility that supplies drinking water citywide. It reviews properties case by case rather than applying one blanket rule. Commercial sites, industrial users near Ontario International Airport and the logistics buildings off I-10, SR-60 and I-15 are the usual candidates, along with irrigation and fire services. If you aren't sure, the division can be reached at backflow@ontarioca.gov or (909) 395-2678, and it can tell you whether an assembly on your account is on file.

How does the yearly test and filing work here?

The owner or customer is responsible for having every required assembly tested at least annually. The tester must be certified and approved by the City, and results go in through the City's online tester portal; paper reports are not accepted. That last point catches people out when they hire someone used to mailing forms in other cities, so confirm the tester can file in Ontario's system before the appointment. Ontario's water is a mix of city groundwater, imported water and purchased groundwater, and the 2025 report lists hardness averaging 124 mg/L for city wells and up to 137-177 mg/L for purchased groundwater, so scale on check seats is a real cause of failed tests.

What happens if my assembly fails?

You have 30 days to repair or replace it and get a passing retest on file. Most failures come down to worn rubber, a weak spring or debris holding a check open, and a rebuild kit solves many of them. A cracked body, a unit that is no longer an approved model or repeated failures usually mean replacement. New installations or relocations can need a permit from the City of Ontario Building Department, which takes applications through its online Citizen Portal Access site.

A note for Ontario Ranch and older neighborhoods

Ontario was planned in 1881 as an irrigated citrus colony and now runs from older blocks near Euclid Avenue and Downtown Ontario to new subdivisions in Ontario Ranch. Newer communities often have shared landscape meters managed by an HOA, while older commercial strips may have assemblies that were installed decades ago. Either way, the 30-day repair window is short, so book the follow-up visit as soon as a test fails.